We extend to you a cordial "WELCOME ABOARD !" Come on in, make yourself at home, we are a friendly group of enthusiasts, and we also appreciate the classic Chris Craft Roamer, Corsair, and Lancer boats too , as they are all on the same family tree and share much in common !
The following is from a very informed FE engine guy who I rely on from time to time for good info.
"The 1973-76 390-4V pickup truck engine has the same intake, except it has an EGR boss cast in. Most EGRs are drilled, some are not. A 1973-76 4V intake without the drilled boss, or with the boss plugged, would perform identically to that marine intake."
I do have a spare and I will check the numbers on it this eve just to know what they are and I'll look it over closely to see if I can distinguish any problems. If you need an authentic marine unit I'll sell it for under market value. I just want to be sure it is a good spare before going to the trouble to box, ship, install, and then discover something wrong. I'll check on it tonight and I'll get back, in the meantime if you find one locally that is from a 390 truck (or auto, for that matter as long as it is not a high performance intake) it should fit just fine. The intakes are nothing special on marine motors, they are for torque and not high performance.
Ford did a great job of "parts bin engineering" with the marine motors. They used the royal blocks, and a fine cast iron crankshaft (exception: some or all side oilers may have received steel cranks but in our application, cast iron cranks are more than adequate), generic intakes and heads, a torque cam, generic rods and pistons, and the result was one of the best marine motors ever built.